Appendix A. Managing your squeeze system before the upgrade

This appendix contains information on how to make sure you can install or
upgrade squeeze packages before you upgrade to wheezy. This should only be
necessary in specific situations.

A.1. Upgrading your squeeze system

Basically this is no different from any other upgrade of squeeze you've been
doing. The only difference is that you first need to make sure your package
list still contains references to squeeze as explained in Section A.2, “Checking your sources list”.

If you upgrade your system using a Debian mirror, it will automatically be
upgraded to the latest squeeze point release.

A.2. Checking your sources list

If any of the lines in your /etc/apt/sources.list refer to
'stable', you are effectively already “using” wheezy. This
might not be what you want if you are not ready yet for the upgrade. If
you have already run
apt-get update, you can still get back without problems
by following the procedure below.

If you have also already installed packages from wheezy, there probably
is not much point in installing packages from squeeze anymore. In
that case you will have to decide for yourself whether you want to continue or
not. It is possible to downgrade packages, but that is not covered here.

Open the file /etc/apt/sources.list with your favorite
editor (as root) and check all lines beginning with
deb http: or deb ftp: for a reference to
“stable”. If you find any, change
stable to squeeze.

If you have any lines starting with deb file:, you will have
to check for yourself if the location they refer to contains an
squeeze or a wheezy archive.

Important

Do not change any lines that begin with deb cdrom:.
Doing so would invalidate the line and you would have to
run apt-cdrom again. Do not be alarmed if a
'cdrom' source line refers to “unstable”.
Although confusing, this is normal.

If you've made any changes, save the file and execute

# apt-get update

to refresh the package list.

A.3. Removing obsolete configuration files

Before upgrading your system to wheezy, it is recommended to remove old
configuration files (such as *.dpkg-{new,old} files under
/etc, as well as the file
/etc/X11/XF86Config-4[6]) from
the system.

A.4. Upgrade legacy locales to UTF-8

If your system is localized and is using a locale that is not based on UTF-8
you should strongly consider switching your system over to using UTF-8 locales.
In the past, there have been bugs[7] identified that manifest themselves
only when using a non-UTF-8 locale. On the desktop, such legacy locales are
supported through ugly hacks in the library internals, and we cannot decently
provide support for users who still use them.

To configure your system's locale you can run dpkg-reconfigure
locales. Ensure you select a UTF-8 locale when you are presented
with the question asking which locale to use as a default in the system. In
addition, you should review the locale settings of your users and ensure that
they do not have legacy locale definitions in their configuration
environment.

[6] Since release
2:1.7.7-12, xorg-server no longer reads the file XF86Config-4. See also #619177.

[7] In the GNOME screensaver, using
passwords with non-ASCII characters, pam_ldap support, or even the ability to
unlock the screen may be unreliable when not using UTF-8. The GNOME screenreader is
affected by bug #599197.
The Nautilus file manager (and all glib-based programs, and likely all Qt-based
programs too) assume that filenames are in UTF-8, while the shell assumes they
are in the current locale’s encoding. In daily use, non-ASCII filenames are
just unusable in such setups.
Furthermore, the gnome-orca screen reader (which grants sight-impaired users
access to the GNOME desktop environment) requires a UTF-8 locale since Squeeze;
under a legacy characterset, it will be unable to read out window information
for desktop elements such as Nautilus/GNOME Panel or the Alt-F1
menu.